The present invention generally relates to isometric muscle testing apparatus used for testing the performance of different body parts of a human subject, and particularly to the transducer mechanism for the apparatus which acts to generate and send to a monitoring device an electrical signal which is proportionate to a physical force applied to the transducer.
Muscular and neuromuscular disorders can be diagnosed by a qualified health professional using various developed procedures for testing individual muscles or muscle groups. The types of testing procedures developed for this purpose can be divided into three general categories: isometric, isokinetic, and isotonic. Generally, these testing procedures require the stabilization of the patient's body, instructing the patient to exert a force by a limb or other body part against a reacting force in a prescribed manner which isolates the muscle or muscle groups being tested, and sensing the force being exerted. For example, an isometric testing procedure for testing the left lateral deltoid muscle, calls for the patient, while in a sitting position to hold his or her arm out in a horizontal position, bent at the elbow, and to push upwardly with the upper arm against a counter-resisting force applied above the elbow.
Muscle testing procedures were initially developed to be practiced manually: the health professional would grip or hold his or her hand against the patient's limb or body part being tested, instruct the patient to exert a force by that limb or body part in a specified manner, and apply the required counterforce while subjectively sensing the amount of pressure being exerted by the patient. From manual sensation of exerted pressures, a diagnosis would be made, for example, from a sensed pattern of weakness in a muscle or muscle group, or an imbalance between the same muscles on the left and right side of the body.
Because of the subjectivity of manual muscle testing techniques, mechanical muscle testing machines have been devised which sense and provide an objective record of the force exerted by the patient. Examples of such equipment are disclosed in U.S. Pat. Nos. 3,374,675, to Michael Keropian; 3,752,144 to Keith E. Weigle, Jr.; and 4,732,038 to Daniel Del Giorno, et al. The foregoing patents disclose isometric muscle testing machines having a force sensing transducer device held on an upright frame and adjustment mechanisms for positioning the transducer to different heights and angles as required by the health professional. Such testing machines are relatively difficult and time consuming to use in that the angle of the force sensing transducer must, normally, repeatedly be readjusted in the course of a single testing session. Also, proper use of the apparatus normally calls for the recording of each transducer head angle.
The present invention provides a transducer head for a muscle testing apparatus which for most test procedures eliminates the need for any adjustment of the force sensing element used for the test other than an easily made height adjustment. The invention also provides a transducer head which, within a single height adjustable unit, can be used for a wide variety of tests, namely, test procedures requiring pushing forces, tests requiring a pull force, and grip strength tests. The invention further provides a transducer design wherein relatively inexpensive transducer elements can be employed and wherein a variety of electronic options can be provided within a single adjustable unit.